Touch screens may be classified into categories such as resistive touch screens, self-capacitive touch screens, and mutual-capacitive touch screens according to their different operating principles. Among them, the mutual-capacitive touch screens have advantages such as high sensitivity and multi-touch, and are used more and more widely.
Specifically, a mutual-capacitive touch screen includes touch driving electrodes and touch sensing electrodes that are crossing and insulated from each other. Mutual capacitors are formed between touch driving electrodes and touch sensing electrodes. When a finger touches the touch screen, capacitance values of the mutual capacitors are changed, and thereby signals from the touch sensing electrodes are changed accordingly. A position of the finger touch may be accurately detected by scanning the touch driving electrodes line by line and obtaining the signals from the touch sensing electrodes. A mutual capacitive touch screen is typically embedded in a liquid crystal display (LCD), i.e. the touch driving electrodes and the touch sensing electrodes are arranged within the LCD, so as to improve light transmissibility, reduce a thickness of the LCD and reduce cost for manufacturing the touch screen.
The inventors of the present application find out that, when the mutual capacitive touch screen is embedded in the LCD, the capacitance values of the mutual capacitors are affected by deflection of liquid crystal molecules, i.e. dielectric coefficients of dielectrics between the touch driving electrodes and the touch sensing electrodes are changed when the liquid crystal molecules at a position are deflected, and thereby the capacitance values of the mutual capacitors are changed accordingly. Thus, the signals from the touch sensing electrodes are changed. As a result, a position of the finger touch might be difficult to be detected accurately due to the fact that a difference caused by the finger touch and the deflection of the molecules cannot be determined because of uncertainty of the deflections of the molecules.